A conventional method of forming color images using a light-sensitive silver halide photographic material is based on reaction of a photographic coupler with the oxidant of a color developing agent. The typical photographic couplers used for color reproduction include magenta, yellow and cyan. The typical color developing agents used include aromatic primary amines. Dyes such as azomethine dyes are formed through reaction of dye-forming couplers such as magenta- or yellow-dye-forming coupler with an oxidant of aromatic primary amine color developing agent. Dyes such as indoaniline dyes are produced through reaction of the cyan coupler with an oxidant of the aromatic primary amine color developing agent.
Among these dyes 5-pyrazolone, cyanoacetophenone, indazolone, pyrazolobenzimidazole, pyrazolotriazole couplers are used to form magenta dye images.
In the past, the 5-pyrazolone coupler has been practically used mainly as the magenta dye image-forming coupler. The dye images formed from the 5-pyrazolone coupler are highly resistant to light and heat, while its color tone is not sufficient. Further, dyes of this class have an unnecessary spectrum absorption near 430 nm and the absorption spectrum of visible light near 550 nm is broad, which causes color turbidity, resulting in less clear photographic images.
As the couplers providing no such unnecessary absorption, there have been known 1H-pyrazolo [3,2-c]-s-triazole type couplers, 1H-imidazo [1,2-b]-pyrazole type couplers, 1H-b pyrazolo [1,5-b]-pyrazole type couplers, and 1H-b pyrazolo [1,5-d] tetrazole type couplers, which are disclosed in U.S. Pat. No. 3,725,067, Japanese Patent Publication Open to Public Inspection No. 162548/1984, and Japanese Patent Publication Open to Public Inspection No. 171956/1984.
The light stability of the color images formed by these couplers, however, is very low and, therefore, it has been considered in the art that the use of such couplers for light-sensitive material especially for color photographic papers which are subject to direct appreciation, does not meet critical requirements of recording and preserving the original image. This has prevented the couplers from being used practically.
To improve light resistance, use of phenol compounds or phenyl ether compound as anti-oxidants has been proposed, for example, in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) No. 125732/1984 This, however, has provided no sufficient effects.
On the other hand, use of a metal complex as the antifading agent has been presented in Japanese Patent O.P.I. Publications No. 99340/1981, 168652/1981 and 51834/1985. Application of the metal complex to dyes from certain class of pyrazolotriazole couplers can improve the light resistance, however, compounds providing relatively high light resistance, are often accompanied by such a disadvantage that non-exposed samples tend to result in increased fog with the lapse of time. Some compounds obtained from a metal complex, which cause less foggind during storage do not provide sufficient resistivity to light.
Thus it has been difficult to improve light resistivity of light-sensitive silver halide photographic materials while keeping resistance against fogging during storage when a pyrazolotriazole system magenta coupler and a metal complex are used in combination.